This environment is part of the Atari environments. Please read that page first for general information.

Action Space


Observation Space

(210, 160, 3)

Observation High


Observation Low





The object of the game is to score as many points as you can while controlling Mother Kangaroo to rescue her precious baby. You start the game with three lives. During this rescue mission, Mother Kangaroo encounters many obstacles. You need to help her climb ladders, pick bonus fruit, and throw punches at monkeys. Detailed documentation can be found on the AtariAge page


By default, all actions that can be performed on an Atari 2600 are available in this environment. Even if you use v0 or v4 or specify full_action_space=False during initialization, all actions will be available in the default flavor.


By default, the environment returns the RGB image that is displayed to human players as an observation. However, it is possible to observe

  • The 128 Bytes of RAM of the console

  • A grayscale image

instead. The respective observation spaces are

  • Box([0 ... 0], [255 ... 255], (128,), uint8)

  • Box([[0 ... 0] ... [0  ... 0]], [[255 ... 255] ... [255  ... 255]], (250, 160), uint8)

respectively. The general article on Atari environments outlines different ways to instantiate corresponding environments via gym.make.


Your score will be shown at the top right corner of the game. Your end game score with be dependent on how much time you have remaining and who you encounter along the way. For a more detailed documentation, consult the AtariAge page.


env = gym.make("ALE/Kangaroo-v5")

The various ways to configure the environment are described in detail in the article on Atari environments. It is possible to specify various flavors of the environment via the keyword arguments difficulty and mode. A flavor is a combination of a game mode and a difficulty setting.


Valid Modes

Valid Difficulties

Default Mode


[0, 1]



You may use the suffix “-ram” to switch to the RAM observation space. In v0 and v4, the suffixes “Deterministic” and “NoFrameskip” are available. These are no longer supported in v5. In order to obtain equivalent behavior, pass keyword arguments to gym.make as outlined in the general article on Atari environments. The versions v0 and v4 are not contained in the “ALE” namespace. I.e. they are instantiated via gym.make("Kangaroo-v0").

Version History#

A thorough discussion of the intricate differences between the versions and configurations can be found in the general article on Atari environments.

  • v5: Stickiness was added back and stochastic frameskipping was removed. The entire action space is used by default. The environments are now in the “ALE” namespace.

  • v4: Stickiness of actions was removed

  • v0: Initial versions release (1.0.0)